Low part count blower-motor assembly in common housing

ABSTRACT

A low part count blower-motor assembly in a two-part housing which defines fluid inlet and discharge openings for the blower but which is otherwise sealed when assembled. An integrated tubular stator subassembly is fixedly attached to one of the housing parts and projects axially toward the fluid inlet opening. An integrated motor rotor subassembly is also disposed within the housing for rotation about the stator subassembly in coaxial relationship therewith, a part of the rotor subassembly being disposed axially between the stator and the inlet opening in spaced relationship with the opening. A shaft is journaled in the central opening of the tubular stator subassembly and projects axially there from toward the inlet opening and a fluid impeller mounted on the projecting end portion of the shaft receives fluid from the inlet opening. The impeller is also fixedly attached to the part of the rotor which resides between the stator and inlet opening.

RELATED APPLICATION

Provisional application No. 60/508,414, titled “Blower with motor sealedinside” filed Oct. 2, 2003, inventors Robert A. Hoyt, David A. Curtisand Russel H. Marvin, incorporated herein by reference.

BACKGROUNG OF THE INVENTION

Typical blower-motor assemblies include at least three majorsubassemblies, the blower or impeller, an electric motor driving theblower, and one or more housings.

Part counts in these assemblies is high due primarily to the complexityof the electric motors and this of course leads to relativelyinefficient assembly and manufacturing procedures. Conventionally, themotor is an external component and is connected in driving relationshipwith the blower by a drive shaft which passes through a blower housing.This arrangement results in high noise generation, air leakage at theshaft opening in the blower housing, air leakage through the motorbearings, and motor cooling problems if the blower is contained withinan enclosed space.

It is a general object of the present invention to provide a low partcount blower-motor assembly in a common housing whereby to eliminate airleakage between the motor and blower wheel thus improving performance,reducing noise generation, enhancing motor cooling, and protecting themotor from harmful environmental conditions. A further object of theinvention is to provide for improved cooling of the motor by diverting aportion of the main air stream passing through the blower and directingit through the motor stator.

Another object of the invention is to provide integrated unitary statorand rotor assemblies, and in some instances integrated unitary rotor andblower or impeller assemblies thus aiding in minimizing part counts.

Finally, an important object of the invention is to provide ablower-motor assembly wherein at least the shaft and motor bearings arearranged in a housing in such a manner that there is no significantpressure drop across the bearings.

SUMMARY OF THE INVENTION

In accordance with the present invention and in fulfillment of theforegoing objects a two-part housing is provided and defines fluid inletand discharge openings for a blower. The housing is otherwise sealedwhen the parts are joined together in assembly. An integrated tubularstator subassembly is fixedly attached to one of the housing parts andprojects toward the fluid inlet opening. A motor rotor assembly which isalso integrated is disposed within the housing in coaxial relationshipwith the stator assembly for rotation thereabout part of the rotorassembly being located axially between the stator and the inlet openingin the housing. A shaft is journalled in the central opening in thetubular stator and projects axially toward the inlet opening in thehousing. Mounted on the projecting end portion of the shaft is a fluidimpeller adapted to receive fluid from the inlet opening, the shaftbeing attached to the part of the rotor residing between the stator andthe inlet opening and driven thereby.

Motor cooling is provided by openings connecting the interior of thestator and the upstream and downstream sides of the impeller, at leastone of said openings having a flow-regulating device.

Preferably the construction of the stator assembly is in accordance withthe teaching of U.S. application Ser. No. 10/679,143, Improved PermanentMagnet Motor, filed Oct. 2, 2003, herein incorporated herein byreference, with the entire assembly overmolded in an injection moldingprocess resulting in a unitary component. Similarly, the rotor assemblyis preferably constructed in accordance with the teaching of U.S.Application 60/508,413, Method for Making Rotor for Permanent MagnetElectric Machine, filed Oct. 2, 2003, herein by reference, with theentire assembly overmolded in am injection molding process resulting ina unitary component. A bearing tower, to be described herein below, isalso constructed in accordance with the teaching of U.S. Application60/442,407, herein by reference, with the entire assembly overmolded inan injection molding process resulting in a unitary component.Additionally, it should be noted that the rotor may be molded integrallywith the impeller, thus further reducing the number of parts.

Finally, and in accordance with another aspect of the invention, theaforesaid integral components and other features are not essential, andit is only necessary the assembly be designed in a general way toprovide the absence of any significant pressure drop across the bearingsand the diversion of a portion of the main fluid flow from the impellerfor flow through the motor and cooling of the same.

DESCRIPTION OF THE DRAWINGS

FIG. 1 of the drawings is a sectional view through the blower-motorassembly of the invention,

FIG. 2 is a sectional view similar to FIG. 1 but taken one hundredtwenty degrees removed from the FIG. 1 view,

FIG. 3 is a fragmentary section similar to FIG. 2 showing connectingscrews between the rotor and stator,

FIG. 4 is a further fragmentary section similar to FIG. 3 but showingregulating plugs installed in air passageways connecting the interior ofthe stator with a low pressure area near the impeller inlet,

FIG. 5 is a sectional view similar to FIG. 2 but emphasizing the unitaryresult and overmolding construction of the stator and rotor assemblies.

DESCRIPTION OF PREFERRED EMBODIMENT

Referring to FIG. 1, a low part count blower-motor assembly is indicatedgenerally at 10 and includes upper and lower parts 12 and 14. The partsare adapted for snap-fit engagement at a tongue and groove joint 16. Theupper part 12 carries a stator assembly 18 attached to the housing byscrews 20, 20 (one shown) and which may be conventional or which mayfollow the teaching of the above mentioned U.S. application Ser. No.10/679,143. The stator is tubular with annular windings at 19 and abearing tower 22, which may be constructed in accordance with theaforementioned U.S. Application 60/442,407, supported in its centralopening 24 in turn carries front and rear bearing units 26 and 28. Thebearing units 26, 28 journal a shaft 30 which projects downwardly fromthe central opening of the stator toward a fluid inlet opening 32 on thelower or second housing part 14. A discharge opening is formedcooperatively by the two housings parts 12 and 14 at 33.

Supported by the stator assembly 18 for rotation thereabout is a rotorassembly 34 which may be conventional or which may follow the teachingof the aforementioned U.S. Application 60/508,413. The rotor assembly 34carries one or more permanent magnet 36, 36 and has a radially extendingpart 38 which resides between the stator and the inlet opening 32.

A blower or impeller, shown as an air impeller 40, is mounted on theprojecting end portion of the shaft 30 and rotor 38, which is then heldin its axial proximity relative to the stator by screws 42, 42 whichattach the stationary spring 54, 54 of the rotor to the stator assemblyand is shown attached to the rotor part 38 by screws 42, 42, FIGS. 3, 4,and 5.

As will be apparent, the impeller 40 will draw air in through the inlet32 and discharge the same radially outwardly under pressure as indicatedby the arrows 44, 44 in FIG. 2. As is also indicated by the arrows 44,44 the main air stream air makes a right angle turn upwardly along thewall of the lower housing part 14 and then leaves the housing throughthe discharge opening 33 after a second right angle turn. As indicatedby the arrows 46, 46, a portion of the main air stream is divertedupwardly and radially inwardly at the top of the housing and enters thestator interior through openings 48, 48, one shown. The diverted orcooling air stream represented by the arrows 46, 46 continues downwardlythrough the central opening of the stator about the bearing tower 22 andexits through openings 50, 50 to the relatively low pressure areaadjacent the inlet of the impeller, FIG. 3. The bearings and windings,critical components, are thus cooled in a highly efficient manner.

Referring to FIG. 4, plugs 52, 52 are provided for the openings 50, 50and may serve as air flow regulating devices. That is, by properlydimensioning the plugs relative to their respective openings to regulateleakage or, for example, by providing vent openings of selected size,the air discharge area can be altered and the cooling effect regulated.From the foregoing, it will be apparent that an extremely low countblower assembly has been provided with the motor and blower in a compactarrangement in a common housing and with novel and highly effectivecooling provisions for the motor.

1. A low part count blower-motor assembly in a common housing comprisinga two-part housing which defines fluid inlet and discharge openings forthe blower but which is otherwise sealed when assembled, an integratedtubular stator subassembly fixedly attached to one of the housing partsand projecting axially toward the fluid inlet opening, an integratedmotor rotor subassembly disposed within the housing for rotation aboutthe stator subassembly in coaxial relationship therewith, a part of therotor subassembly being disposed axially between the stator and theinlet opening in spaced relationship with the opening, a shaft journaledin the central opening of the tubular stator subassembly and projectingaxially from the opening toward the inlet opening, and a fluid impellermounted on the projecting end portion of the shat to receive fluid fromthe inlet opening, said impeller also being fixedly attached to saidpart of the rotor residing between the stator and the inlet opening. 2.A low part count blower-motor assembly in a common housing as set forthin claim 1 wherein openings are provided respectively for communicationbetween the interior of the stator subassembly and the upstream anddownstream sides of the impeller, a flow of cooling fluid through thestator subassembly thus being provided.
 3. A low part count blower-motorassembly in a common housing as set forth in claim 2 wherein a flowregulating device is provided for at least one of said stator openingswhereby to control cooling of the motor.
 4. A low part countblower-motor assembly in a common housing as set forth in claim 3wherein the fluid is air, and wherein the flow regulating device is aplug in the associated opening and having an air flow passageway ofpredetermined area for controlling air flow through the stator.
 5. A lowpart count blower-motor assembly in a common housing as set forth inclaim 1 wherein the stator subassembly is overmolded in a plasticinjection molding process to provide a unitary subassembly.
 6. A lowpart count blower-motor assembly in a common housing as set forth inclaim 1 wherein the rotor subassembly is overmolded in a plasticinjection molding process to provide a unitary subassembly.
 7. A lowpart count blower-motor assembly in a common housing as set forth inclaim 1 wherein both the stator and rotor subassemblies are overmoldedin plastic injection molding operations to provide unitarysubassemblies.
 8. A low part count blower-motor assembly in a commonhousing as set forth in claim 1 wherein the impeller is ultrasonicallywelded to the rotor part residing between the stator and the inletopening.
 9. A low part count blower-motor assembly in a common housingas set forth in claim 1 wherein the rotor and impeller are integrallymolded simultaneously.
 10. A low part count blower-motor assembly in acommon housing as set forth in claim 1 wherein the housing parts areadapted for snap-fit interengagement.
 11. A blower-motor assemblywherein at least the motor bearings and shaft are located in the blowerhousing in such a manner that no significant pressure drop occurs acrossthe bearings, the motor including fluid flow passageways which divert aportion of the main fluid flow stream generated by the blower into oneof said passageways through the motor and then out another of saidpassageways to rejoin the main fluid flow stream whereby to cool themotor.
 12. A blower-motor assembly in a common housing which definesinlet and discharge openings for the blower but which is otherwisesealed, an annular stator fixedly attached to the housing and a rotorcarried by the stator for rotation thereabout and in turn driving afluid impeller, a shaft mounted within axially spaced bearings in thecentral opening of the tubular stator, inlet and discharge openings inthe stator arranged to divert a portion of the main fluid streamgenerated by the impeller through the stator and thereby cooling themotor.
 13. A blower-motor assembly as set forth in claim 12 wherein thefluid flow passageways are arranged to draw fluid from the downstreamside of the blower and discharge the cooling air to the upstream side ofthe blower.
 14. A blower motor assembly as set forth in claim 12 whereinthe fluid flow passageways are arranged to draw fluid from thedownstream side of the blower and discharge the cooling air to theupstream side of the blower but sub impeller for blower.
 15. Ablower-motor assembly as set forth in claim 14 wherein both the statorand rotor are of overmolded plastic construction.